- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Critical Behavior of Ni-doped La0.7Sr0.3MnO3 Ceramics
摘要： The effect of Ni substitution on the magnetic properties and the critical behavior of La0.7Sr0.3Mn1-xNixO3 compounds, which were prepared by the solid-state reaction method has been investigated. Based on our investigations of the temperature and the magnetic field dependences of magnetization M(T, H) data, it is shown that the Curie temperature (TC) of La0.7Sr0.3Mn1-xNixO3 compounds will be shifted toward room temperature with increasing Ni concentration (x), TC = 359–307 K for x = 0.0–0.1. By using the modified Arrott plots and the Kouvel–Fisher methods together with M(H, T) data in the vicinity of the ferromagnetic (FM)–paramagnetic phase transition, the critical exponents (β, γ, and δ) have been determined. Our results show the existence of a short-range FM order in the undoped sample (x = 0). The values of β, γ, and δ will be shifted gradually toward those of the mean-field theory when x increases, suggesting that the long-range FM order is favored in Ni-doped samples. The results calculated on the effective exponents of β_eff(ε) and γ_eff(ε) in the asymptotic region indicate the existence of a magnetic disorder in all the samples.
关键词： manganites,ferromagnetic order,Critical behavior
更新于2025-09-23 15:23:52
-
Correlation between magneto-optical and transport properties of Sr doped manganite films
摘要： The features of electronic structure of La0.7Sr0.3MnO3, Pr0.8Sr0.2MnO3, and Pr0.6Sr0.4MnO3 polycrystalline films of different thickness have been investigated using magnetic circular dichroism (MCD) in the range of 1.1e4.2 eV. The temperature behavior of the samples electrical resistance were also has been studied. It was found that films with high Sr content (0.3 and 0.4) act as high-temperature semiconductors, while the maximum in the temperature dependences of resistivity these films indicates the transition of the samples to the metallic state at some temperature TM-S, which is different for different sample thickness. The films with the lower Sr content (0.2) act as insulators in the used temperature range. The MCD spectra have been decomposed to the Gaussian-shaped lines, and the temperature dependence of intensity of each line has been analyzed in comparison with temperature dependence of the films magnetization and with their electric conductivity type. Different temperature behavior of the intensity of four specified Gaussian-lines was revealed for semiconductor films. In the case of insulating Pr0.8Sr0.2MnO3 samples, the intensity of three specified Gaussian lines changes with the temperature in the same way as the magnetization changed. It was established that the lanthanide (La, Pr) type does not affect the MCD spectra shape for the films with the same electrical conductivity type. Besides, the correlation between the MCD data of the films and their conductivity type was revealed. Due to the detailed analysis of the specified Gaussian lines with taking into account the well-known in the literature absorption bands, lying outside the studied spectral region, the MCD bands for the studied manganite films have been identified with electronic transitions of a different nature.
关键词： Magnetic circular dichroism,Thin films,Electronic properties,Electrical transport,Crystal structure,Manganites
更新于2025-09-23 15:23:52
-
A comparative study of Sr-doped LaMnO <sub/>3</sub> synthesised via solid-state reaction and sol–gel methods
摘要： This work deals with the synthesis of hole-doped La1-xSrxMnO3 (x = 0.25 and 0.33) perovskite via two different ways, namely a solid-state reaction method and a sol–gel process. Various properties of the samples have been investigated and compared by means of different techniques, namely X-ray diffraction (XRD), temperature-dependent resistivity measurements in the temperature range 25–300 K using a closed cycle refrigerator and vibrating sample magnetometry (VSM). All samples have orthorhombic crystal symmetry and an irregular variation in unit-cell volume with increase in Sr content. The average crystallite size was determined from the XRD data and found to lie in the range 19–22 nm. Metal–insulator transitions (MIT) were observed in all the samples via low-temperature electrical characterisations. The magnetic measurements confirm that the magnetisation does not saturate for the 25% Sr doped samples up to the available field of 10 kOe. The magnetic response also supports the interpretation of XRD and resistivity data. The obtained results are explained on the basis of double-exchange and super-exchange mechanisms.
关键词： CMR,manganites,metal to insulator transition (MIT),sol–gel method,Solid-state reaction
更新于2025-09-23 15:22:29
-
Floating zone furnace equipped with a high power laser of 1kW composed of five smart beams
摘要： A floating zone furnace is a powerful tool for single crystal growth. Here, we report the floating zone furnace using a high power diode laser of 1kW composed of five 200 Watt heating beams. The five beams with the designed irradiation intensity distribution enable the melt-growth of single crystals for refractory materials having a high melting temperature above 2000°C, volatile materials and even incongruent materials. The power of five beams in the horizontal plane provides uniform intensity in the outer circumference of the raw material rods, while the vertical direction power of five beams can be made to have a bell shape irradiation intensity so as to relax residual thermal stress in the grown single crystal. The present furnace enables one to directly monitor the temperature of the hot spot of raw material and the molten zone within a 1 mm diameter. Such an in-situ monitoring function of the temperature on the molten zone greatly enhances the controllability for optimizing the crystal growth condition.
关键词： B1. Oxides, Sulfides, Tellurides, Manganites, Borates, Chalcognites,A2. Floating zone technique;,B3. Laser diodes
更新于2025-09-12 10:27:22
-
Review of photoinduced effect in manganite films and their heterostructures
摘要： Light–matter interaction plays an important role in the non-equilibrium physics, especially in strongly correlated electron systems with complex phases. Photoinduced effect can cause the variation in the physical properties and produce some emergent phases. As a classical archetype, manganites have received much attention due to their colossal magnetoresistance (CMR) effect and the strong interaction of charge, spin, orbital, and lattice degrees of freedom. In this paper, we give an overview of photoinduced effect in manganites and their heterostructures. In particular, some materials, including ZnO, Si, BiFeO3 (BFO), titanate-based oxides, and 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) have been integrated with manganites. Heterostructures composed of these materials display some exciting and intriguing properties. We do hope that this review offers a guiding idea and more meaningful physical phenomena will be discovered in active areas of solid state physics and materials science.
关键词： heterostructures,photoinduced effect,manganites
更新于2025-09-09 09:28:46